package com.kevin.nettyrpcprovider.handler;

import com.alibaba.fastjson.JSON;
import com.kevin.nettyrpcapi.common.RpcRequest;
import com.kevin.nettyrpcapi.common.RpcResponse;
import com.kevin.nettyrpcprovider.anno.RpcService;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import org.springframework.beans.BeansException;
import org.springframework.cglib.reflect.FastClass;
import org.springframework.cglib.reflect.FastMethod;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

import java.lang.reflect.InvocationTargetException;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

/**
 * @Author LXL
 * @Date 2021/9/28 9:48
 * 1.将标有@RpcService注解的bean
 * 2.接受客户端请求
 * 3.根据传递过来的beanName从缓存中查找对应的bean
 * 4.解析请求中的方法名称，参数类型，参数信息
 * 5.反射调用bean的方法
 * 6.给客户端进行相应
 **/
@Component
@ChannelHandler.Sharable
public class RpcServerHandler extends SimpleChannelInboundHandler<String> implements ApplicationContextAware {

    private static final Map SERVICE_INSTANCE_MAP = new ConcurrentHashMap();


    @Override
    protected void channelRead0(ChannelHandlerContext channelHandlerContext, String msg) throws Exception {
        //接受客户端请求-将msg转化为RpcRequest对象
        RpcRequest rpcRequest = JSON.parseObject(msg, RpcRequest.class);
        RpcResponse rpcResponse = new RpcResponse();
        rpcResponse.setRequestId(rpcRequest.getRequestId());
        try {
            //业务处理
            rpcResponse.setResult(doHandle(rpcRequest));
        }catch (Exception e){
            e.printStackTrace();
            rpcResponse.setError(e.getMessage());
        }


        //6.给客户端进行相应
        channelHandlerContext.writeAndFlush(JSON.toJSONString(rpcResponse));
    }

    /**
     * 业务处理逻辑
     *
     * @param rpcRequest
     * @return
     */
    private Object doHandle(RpcRequest rpcRequest) throws InvocationTargetException {
        //* 3.根据传递过来的beanName从缓存中查找对应的bean
        Object serviceBean = SERVICE_INSTANCE_MAP.get(rpcRequest.getClassName());
        if (serviceBean == null){
            throw new RuntimeException("根据beanName找不到服务,beanName:" + rpcRequest.getClassName());
        }
        //* 4.解析请求中的方法名称，参数类型，参数信息
        Class<?> serviceBeanClass = serviceBean.getClass();
        String methodName = rpcRequest.getMethodName();
        Class<?>[] parameterTypes = rpcRequest.getParameterTypes();
        Object[] parameters = rpcRequest.getParameters();
        //* 5.反射调用bean的方法 使用cglib
        FastClass fastClass = FastClass.create(serviceBeanClass);
        FastMethod method = fastClass.getMethod(methodName, parameterTypes);
        return method.invoke(serviceBean, parameters);
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        Map<String, Object> serviceMap = applicationContext.getBeansWithAnnotation(RpcService.class);
        if (serviceMap != null && serviceMap.size() >0){
            Set<Map.Entry<String, Object>> entries = serviceMap.entrySet();
            for (Map.Entry<String, Object> entry : entries) {
                Object serviceBean = entry.getValue();
                if (serviceBean.getClass().getInterfaces().length  == 0){
                    throw new RuntimeException("服务必须实现接口");
                }
                String beanName = serviceBean.getClass().getInterfaces()[0].getName();
                SERVICE_INSTANCE_MAP.put(beanName, serviceBean);
            }
        }
    }
}
